1. Field of the Invention
The present invention relates to a network topology collection device, and in particular to a network topology collection device for determining a network topology which indicates a connection state of a route.
Recently, with a rapid advancement of a communication technology and a growing demand for communication, the number of nodes (transmission devices) and routes (links) which compose a network has been increasing, a communication rate has been enhanced, the routes in the network have been hierarchized (multiplexed), and a network topology has been complicated.
In such a complicated network, recognition (determination) of a network topology when the nodes and routes are added/changed/removed at the time of a network construction or after the construction has been more and more important for enhancing the reliability of communication.
2. Description of the Related Art
Recognition of the prior art network topology such as a recognition of a connection state after a network construction in an SDH/SONET trunk transmission system requires verifications based on network composition data, which much rely on manual works, resulting in a possibility of wrong network construction.
In order to solve this problem, “Generation method of network composition data and network system using the same” disclosed in the Japanese Patent Application Laid-open No.2000-4227 has proposed a method/system for performing verifying works in real time.
The method and system are characterized in that transmission information carried by transmission part information added thereto is transmitted between interfaces of transmission devices (nodes) mutually connected, the transmission part information received on the reception side and reception part information which receives the transmission part information are stored, and the stored transmission part information and the reception part information are combined to be outputted as device information required from a processor connected to the outside of the transmission device.
When the method and the system are applied to an SDH/SONET network, for example, a connection state of a section can be collected since the collected network composition data are an aggregation of pairs of the transmission part information and the reception part information. However, a connection state of a line and a path may not be collected. Namely, in this method and system, there is a problem that only a network topology of a section within a route where a section, a line, and a path are hierarchized (“multiplexed” in the SDH/SONET network) can be recognized.
Also, the processor is connected to the outside of the transmission device with another transmission line different from one through which communication service information passes. The network composition data are collected through this different transmission line. Accordingly, there is a problem as follows: When the different transmission line through which the network composition data pass is abnormal, the processor can not properly collect the network composition data. Therefore, although the transmission line through which the communication service information passes is normal, the topology of the network composed of the normal transmission line and the transmission device can not be determined.
Furthermore, since the network composition data are collected in real time in the method and the system, the transmission device is always required to keep transmitting the transmission part information and to keep transmitting the network composition data to the processor. The processor is always required to update the network composition data, and to determine the network topology. Accordingly, there is a problem that information transmitted/received between the transmission devices and between the transmission device and the processor is increased, thereby complicating the processing of the processor.